瑜伽論記 7.30

7.30

釋所依，云一、身；二、心。以要依身心，入出息轉如其所應等者，景云：即是婆沙依身依心隨其宜便，隨其宜便者。有說：嬰孫時息少中年時中老年時多。有說：以四事故名隨宜便，一者、依身；二、風道通；三、毛孔開；四、息地麁心現前。

In explaining the basis, it mentions: 1. body; 2. mind. Regarding 'Because it necessarily relies on body and mind, the in-and-out breaths proceed as appropriate', etc.: Jing says that this corresponds to the Vibhāṣā's 'relying on body and relying on mind according to appropriateness'. Regarding 'according to appropriateness', some say: 'In infancy the breath is slight; in middle age it is moderate; in old age it is plentiful.' Others say: 'Because of four factors it is called according to appropriateness: first, relying on the body; second, open breath passages; third, open pores; fourth, the coarse mind of the breath-stage being present.'